Ceiling box has 2 black wires and 1 white wire

Question

I just moved into a newly built condo, and there wasn't a light fixture installed before.

This is what it looks like right now:

There are two wires, black and white, marette'd(?) together, and there is a lone black wire, which had not been stripped.

Ground wire is just bare copper and it's not touching anything.

The LED light fixture I'm trying to install is pretty standard, it has one black and one white wire, and a bare copper ground wire.

I'm not sure which wire goes where!

Here's what I've tried:

1. WHITE 1 with WHITE (light fixture, lf) and BLACK 1 with BLACK (lf)
2. WHITE 1, BLACK 1, with WHITE (lf) altogether and BLACK 2 with BLACK (lf)

In both of these cases, when I turned the circuit breaker back on, the LED lights were very dimly lit, and they did not respond to the light switch at all. They stayed on, very very dim. Did the diodes break?! :'(

Thanks!

Answer 1

The white wire tucked into the back of the box, that isn't stripped or capped, is your actual neutral.

We know that "White 1" is not neutral, because it is spliced to a black wire, and a black wire can only be a hot wire (remarking hot-colored wires to change their purpose is forbidden). Therefore "White 1" is certainly a hot wire, and should have been marked with black tape -- marking white wires to make them hot is allowed.

This means that the remaining loose black wire (surely hot-white's partner) is coming from the switch.

So, the white+black that were already spliced together should not be touched. The lamp needs to take its hot from the solo black wire, and its neutral from the white wire in the back of the box.

I am surprised at the number of mistakes here.

• The white (actual neutral) needed a cap. Neutrals absolutely can be energized with hot voltage; that's why they use insulated wire.
• The other white (always-hot) needed to be marked a hot color (e.g. black). That's been mandatory for over a decade; the person was following the old code which said "unnecessary if the usage is obvious". Was it obvious to you? :) That's why they changed the rule :)
• Wiring a switch loop without a neutral. (the white has been re-tasked to be hot). That's been illegal since 2008? 11?
• If this is conduit, it's legal to omit neutral because it's easy to add later, but it's illegal to remark white wires to be hot (you're using individual wires so you must use the correct color, end of subject).

I would consider having your own electrician come in and do a forensic inspection, and going after the condo association for the cost of going through this work with a fine-tooth comb to look for other mistakes. This is a lot of mistakes for new construction, but the building boom has left them "scraping the bottom of the barrel" for electricians.